HVAC spiral pipe question

I am still running my 3HP dual-bag Grizzly dust collection system without any ductwork. Which means, 20’ 4” hose snaked over the place to get the job done. Frustrating. I played telephone vendor to a HVAC supply house today. Manager was grateful I fix the dialtone issue and we started talking. Told her about my plight of my wallet playing possum everytime I think of the total $ of wood shop ducting. ‘Lo and behold, she offered to help! Here is what she says she can offer:

$7 for 6”x6”x6” wye’s, 26gauge and same for 6×6x4.$11 for 5’ spiral duct 26gauge.are these “wow omg” prices? or standard?

Before this, I was mostly leaning towards PVC so do not know pricing of 26gauge HVAC ductwork. And the spiral duct.. is this better than straight pipe? Does the spiral enhance or degrade any CFM? I had to ask if 26 gauge was better than 28 / 30 gauge like they sell at box stores. Silly me :)Also, they sell dampers. Are they suitable for blast gates? Or too flimsy?

6 replies so far

I used to work in the HVAC industry and those prices are pretty good, especially for something clean that hasn’t been installed before (or beat all to hell by someone moving it around). I still do prefer snap lock tubing for most projects, but a lot of commercial and industrial projects require round spiral duct, that and the snap lock tubing isn’t available over a certain diameter.

I am a retired HVAC sheet metal worker and have installed miles of spiral pipe. In smoke tests spiral pipe leaks badly along the spiral seam. I installed six inch snap lock 24 guage pipe in my shop and used 26 guage ells. A lot less length of seams with this pipe. I made my own Wye’s and blast gates but the prices for the wye’s you mentioned are pretty good. The 30 guage pipe can collapse. I also can recommend using 4” plain round “leader pipe” normally used for downspouts (also called leaders). It is normally 26 guage and comes in ten foot lengths.

thanks block and jim. the snap locks… would this HVAC supply sell them as well? My eye caught straight and spiral. Probably wouldnt of noticed snaplock. Would the snap lock be reasonably 20 or 30% more spendier?

Snap lock pipe will be cheaper than spiral pipe but comes in shorter lengths usually. It needs to be 26 guage so the big box stores usually do not have it. You have to snap it together to make it a round pipe. Easy for me, but can be a struggle if you have not done it before. I would go to an HVAC sheetmetal contractor and talk to them. If I had done my system in four inch instead of six I would have used leader pipe. It is already snapped/spot welded, together and you only have one long straight seam to caulk. You will need a crimper tool to assemble most any sheet metal duct.

+1 to the heavier gauge pipe, I didn’t even use 30 gauge in my house for supply. The big box store (Lowe’s anyway) do have 26 gauge, but only in the short lengths of black or stove pipe. A big HVAC supply house is your best bet for getting the good stuff, usually at a much better price than most large retail outlets. Unfortunately many are wholesale only and you might have to know somebody to get what you need.